Means for cushioning transmission shafts



Aug. 7, 11%23. 1,4642%) K. N. SACHS ET AL MEANS FOR CUSHIONING TRANSMISSION SHAFTS Fiied Dec. 27. 1921 2 Sheets-Sheet 1 BAWLZZQ Aug. 7, 1923.

K. N. SACHS ET AL MEANS FOR CUSHIONING TRANSMISSION SHAFTS Filed Dec. 27. 1.921. 2 Sheets-Sheet 2 Toaliwhomitmeyconcern:

Patented Aug. 7, W233.

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MEANS FOR CUSHIONING: TRANSMISSION SW'IS.

Application filed December 587, 1921.. Serial Ho. 525,117.

Be it known that we, and Joanna SACHS citizens oi the United States, residing'at Iilarttord, in the county of Hartford and State of Connecticut, have invented a new and useful Improvement in Means for Cushioning Transmission Shafts, or which the following is a specification.

This invention relates to those devices which; are designed to be inserted in power transmission systems betweenv the power and the load for the purpose ofeliminating unvm Ni Shorts desirable shock and strain incident to the V inertla'of the parts or sudden variationsin torque of power and load, as on starting a load from rest, or when running the load is suddenly increased or when the load tends to run ahead of the power.

. The object of the invention is to provide *a device of this character which is simple ,to construct and apply and which is strong,

durable and eficient.

'Ihe constructions illustrated as embodying this invention are particularly adapted for insertion in the transmission systems of auto motive vehicles, such as trucks and heavy duty automobiles and motor boats, but of course, they are capable of service in any relation to load.

power transmission lines where it is desirable to reduce or relievethe objectionable effects incident to variatlons of powerwith In the devices shown there is a driving member, a-driven member and a yielding connection between these members that com-- prises a spring cushion and'a fluid check,

the spring by torsion and tension serving to cushion the parts and also restore the check to normal condition, and the check servin to sustain and prevent the viglent action or y the spring. a

In the accompanying drawings 'lFigure 1 shows a central longitudinal section ot a de vice which embodies the invention. Fig. 2 is the form shown in Fig. 5. Fig. 7 shows the other of the check cams used in the form shown in Fig. 5. Fig. 8 is a'view of one end at a device which embodies the invention having a slightly difierent construction, but

producing the same result.

F or the purpose of description 1 will be considered the driving shaft and 2 the driven shaft, but or course this condition could be reversed. The driving shaft extends with a rotatable fit through the head 3 of the cylinder t. In the interior of the cylinder the driving shaft has a plural screw thread 5. At the outer end of the thread the tends through and is-keyed, splined or otherwise rotatably fastened to the head 9 of the' cylinder. This bead hasa hub 10 contminin a hardened socket 11 in which the tip 12 o the driving shaft is 'journalled.

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Closely but movably fitting the inner-wall of the cylinderand also fitting upon the threaded art of the driving shaft is a; piston'13. his piston is free to rotate and to move longitudinally in the cylinder. In the cylinder with one end fastened to the piston and the other end fastened to the head 9, is a spiral springdd. 'Ihe cylinder is filled with oil'or other suitable fluid through the plugged opening 15, and communication on the driven sha t causes the piston to be, turned in on the threaded section on the driving shalt against the elastic llOI'SlODStI and tensional forces of the spring and the bod 0t fluid in the cylinder which has a sma 1 flow only through or pastthe piston, until the reaction of the spring and liquid is suilicient to overcome the inertia of the driven shaft and cause the latter to rotate. As the inertia resistance isovercome due' to the picking up of the load, the torsional and if/BBSIOIlfilflL'GSlllGDCG at the spring co-act to return the piston, as permitted by the flow of fluid from one side to the other, until the balance of forces is restored and then the giyooves desirdrivin shaft rotates the driven shaft threaded section of the driving shaft untilit reaches the nut 7, then the parts become locked together as one piece.

The spring may if desired be in the form of a conical helix 19 as shown in Fig. 4. In this case the piston, that is threaded upon the driving member, may be recessed for recei ving the large end of the spring. T he sinall end of the spring is in this arrangement fastened to a block 20 which is fitted in the head 21 of the cylinder and is held by stiids 22 so that these parts will rotate together. If desired as shown in Fig. 4, check valves such as springcontrolled valves 23 may be arranged in ports in the piston so that when the piston is returned the valves will open and let thefluid flow more freely through the piston on the return movement than on the forward movement. The'forwardmovement of the piston in this case is opposed by the tensional and torsional resilience of the coils of the spring and the rapidity of movement is determined by the flow of fluid through passages24: in the piston or'through grooves 25 in the wall of the cylinder. These grooves if used are desirably tapering, as were the grooves in the previously described form, so that the area of the passages will row smaller and consequently the flow of the liquid will be more restricted as the piston moves forward against the "'ssure of the spring when the driving sha is rotated and resistance is offered to rotation by the load on the driven shaft su'fi may be formed on the head 27 of the driving shaft as shown in Fig. 5. In this case the adjacent end of the piston 28 will have a complementary shaped single thread or spiral cam face'29. This piston is shown as havmg a stud 30 that is fastened to the small end of a conical spring 31, the large end of whlch is fastened to the cylinder near the head 32; A sto plu 33 is set in the'inner wall of the he so t at if the resistance of the load is suflicient to completel overcome the force of the spring, the stu 30 on the piston will abut againstthestud 33 in the ead before the cam surfaces become disengaged and drive the parts. In this form the rotation of the driving shaft causes its head to push the piston forward as fast as the fluid flows past the piston and until the reaction produced by the spring and liquid is equal to the inertia resistance of the driven shaft to the driving force of the driving shaft, at which time the piston will move no further forward but through the spring will rotate the driven shaft. When the relative resistance of the load decreasesthe spring forces the piston back .as fast as the fluid "flows past the piston. (Jrrooves 34 may be formed in the periphery of the piston to permit the fluid to flow from one side to the other.

In the forms above described the driving force is transmitted from the driving shaft to the driven shaft, under normal conditions, through the spring, and the tension of the spring varies under the different relations of the load to the driving power, and in all cases the action of the spring, both when being compressed or returning the piston, is retarded and controlled by the rapidit of flowrof the fluid past the piston which tow,

desirably is slower when the piston moves inward and the load is increasing rather than when the piston is moving outward and the load offers less resistance to the driving force.

In the form shown in Fig,8 the piston 35 is shown as having threads 36 on its outer edge fitting threads 37 cut in the inner wall of the cylinder, so that the piston is free to move rotatably and longitudinally of the cylinder. A contractile spring 38 is arranged in front of the nut' with one end fastened thereto and the other'end fastened to the advanced the spring is drawn out against its torsional and tensional resistance,. which forces are utilized to balance the difference between the inertia of the driving and the I driven shafts.

I In the organizations described the piston is shown, as being free to rotate 1n the cylinder so as to take advantage of the torsional re sistance as well as the tensional resistance of the springs. This actionutilizes all of the resilient qualities of the springs and the springs by their torsional reaction easily return the pistons on the threads back to nor-' m'al positions.

The invention claimed is v 1. Means for cushioning a. transmission.

shaft, comprising a cylinder, an internally threaded piston movable rotatably and longitudinally in the cylinder, a spring interposed between and havin its ends fastened respectively to the cylin er and piston, a driving member and a driven member, one of said members being positively connected with the cylinder and the other meinber being loosely connected with the cylinder and havlib ineaeao positively connected with the cylinder and the other member being loosely connected with the cylinder and bearing means adapted to engage and move the piston longitudinally and rotatably in the cylinder against the tensional and torsional forces of the spring, means for filling the cylinder with fluid, and means permitting a restricted flow of fluid from one side of the piston to the other.

3. Means for cushioning a transmission shaft comprising a cylinder, an internally threaded piston movable longitudinally and rotatably in the cylinder, a spring interposed between and having its ends fastened respectively to the cylinder and piston, a driving member and a driven member, one of said members being positively connected with the cylinder and the other member being loosely connected With the c linder and having a screw thread adapte to engage and move the threaded piston both longitudinally and rotatably in the cylinder against the tensional and torsional forces of the spring, means for filling the cylinder with fluid, and a tapered groove in the wall of the cylinder for permitting a variable flow of fluid from one side of the piston to the other.

d. Means for cushioning a transmission shaft comprising a cylinder, a piston movable longitudinally and rotatably in the cylinder, a spring interposed between and having its ends fastened to the cylinder and piston, a driving member and a driven member, one of said members being positively connected with the cylinder and the other member being loosely connected with the cylinder and bearing means adapted to engage and move the piston longitudinally and rotatably in the cylinder against the .tensional and torsional forces of the spring,

5. Means for cushioning a transmission shaft comprising a cylinder, a driving member connected with the cylinder, a driven member connected with the cylinder, a piston movable rotatably and longitudinally in the cylinder, said piston having a threaded connection with one of said members, and a spring connected to the piston and to the other of said members.

6. ln a transmission cushion, two rotatory members, one of which is a driving and the other a driven member, a piston screw connected to one member and rotatively free from and adapted to be moved longitudinally with relation to the other member by the screw connection, and a spring connected to the piston and to the said other member.

7. In a transmission cushion, two rotatory members one of which is a driving and the other a driven member, a piston screw connected to one member and rotatively free from and adapted to be moved longitudinally with relation to the other member by the screw connection, a spring connected to the piston and to the said other member, and a cylinder containing fluid enclosing the piston.

- KELVllN N. SACHS.

. JQSEPH SACHS. 

